Please use this identifier to cite or link to this item:
https://hdl.handle.net/10316/3897
DC Field | Value | Language |
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dc.contributor.author | Srinivasan, Chandra | - |
dc.contributor.author | Minadeo, Nicole | - |
dc.contributor.author | Toon, Jason | - |
dc.contributor.author | Graham, Daniel | - |
dc.contributor.author | Freitas, Duarte Mota de | - |
dc.contributor.author | Geraldes, Carlos F. G. C. | - |
dc.date.accessioned | 2008-08-29T15:35:48Z | - |
dc.date.available | 2008-08-29T15:35:48Z | - |
dc.date.issued | 1999 | en_US |
dc.identifier.citation | Journal of Magnetic Resonance. 140:1 (1999) 206-217 | en_US |
dc.identifier.uri | https://hdl.handle.net/10316/3897 | - |
dc.description.abstract | Evidence for competition between Li+ and Na+ for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li+ upon the 23Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na+-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed quenching effect of Li+ on the 23Na TQF and DQF signal intensity probed Li+/Na+ competition for isotropic binding sites only. Membrane cytoskeleton depletion significantly decreased the isotropic signal intensity, strongly affecting the binding of Na+ to isotropic membrane sites, but had no effect on Li+/Na+ competition for those sites. Through the observed 23Na DQF NMR spectra, which allow probing of both isotropic and anisotropic Na+ motion, we found anisotropic membrane binding sites for Na+ when the total ionic strength was higher than 40 mM. This is a consequence of ionic strength effects on the conformation of the cytoskeleton, in particular on the dimer-tetramer equilibrium of spectrin. The determinant involvement of the cytoskeleton in the anisotropy of Na+ motion at the membrane surface was demonstrated by the isotropy of the DQF spectra of csdRBC membranes even at high ionic strength. Li+ addition initially quenched the isotropic signal the most, indicating preferential Li+/Na+ competition for the isotropic membrane sites. High ionic strength also increased the intensity of the anisotropic signal, due to its effect on the restructuring of the membrane cytoskeleton. Further Li+ addition competed with Na+ for those sites, quenching the anisotropic signal. | en_US |
dc.description.uri | http://www.sciencedirect.com/science/article/B6WJX-45FKRY3-38/1/bc487aa2e53ceb4bdc5b795e1fbc7ee4 | en_US |
dc.format.mimetype | aplication/PDF | en |
dc.language.iso | eng | eng |
dc.rights | openAccess | eng |
dc.subject | lithium; human red blood cell membranes; cytoskeleton; multiple-quantum-filtered 23Na NMR; 7Li relaxation times | en_US |
dc.title | Competition between Na+ and Li+ for Unsealed and Cytoskeleton-Depleted Human Red Blood Cell Membrane: A 23Na Multiple Quantum Filtered and 7Li NMR Relaxation Study | en_US |
dc.type | article | en_US |
dc.identifier.doi | 10.1006/jmre.1999.1813 | - |
uc.controloAutoridade | Sim | - |
item.fulltext | Com Texto completo | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.grantfulltext | open | - |
item.languageiso639-1 | en | - |
item.openairetype | article | - |
item.cerifentitytype | Publications | - |
crisitem.author.researchunit | CQC - Coimbra Chemistry Centre | - |
crisitem.author.parentresearchunit | Faculty of Sciences and Technology | - |
crisitem.author.orcid | 0000-0002-0837-8329 | - |
Appears in Collections: | FCTUC Ciências da Vida - Artigos em Revistas Internacionais |
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file20c8a80ed9064830b04ad7eb5bcd1d29.pdf | 135.42 kB | Adobe PDF | View/Open |
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